Dynamic Squeeze Flow Hydrodynamics across Ultra Smooth Circuit Foil Interfaces
Dynamic resin squeeze flow across ultra smooth copper foils demands precise thermal press ramping to prevent micro-voiding and hold tightly controlled plane spacing.
Thermal Gelation Rate
Curing Speed
Transition speed from a liquid state to a solid cross linked matrix defines how a prepreg behaves during the lamination process. Measuring the thermal gelation rate helps fabricators determine the window of time available for resin flow before the material hardens. This timing is critical for ensuring that all gaps between copper features are filled.
Curing Mechanism
Heating the laminate initiates chemical reactions that increase the molecular weight of the epoxy or polyimide resin. A fast thermal gelation rate can trap air bubbles if the resin sets before the vacuum press can remove them. Conversely, a rate that is too slow might allow excessive resin to escape the stackup, resulting in a thin board.
Rheology tests measure the change in viscosity over a temperature ramp to find the exact gel point. This data allows engineers to tune the lamination press profile for the specific prepreg batch.
Quality Control
Strong mechanical adhesion depends on the resin fully wetting the treated copper surface before it reaches the gel state. If the thermal gelation rate is inconsistent, the resulting bond may be brittle or prone to delamination. Reliable measurements confirm that the raw material is within its shelf life.